You are using a Vicasso AppExchange application, and encounter an error message which contains the following: "FIELD_CUSTOM_VALIDATION_EXCEPTION".
This error indicates that your organization has a custom validation rule in place that is interfering with the insertion / update of a record.
If you are encountering this error and believe you shouldn't be based on the circumstances, please contact your Salesforce Administrator to track down the problematic validation rule and adjust the criteria to allow for the insertion / update of the record you're working with.
For example, if you are encountering a validation error upon editing a case, check your validation rules on the Case object by navigating to Setup | Build | Customize | Cases | Validation Rules. You'll want to match up the text following "FIELD_CUSTOM_VALIDATION_EXCEPTION" to see which validation rule is causing the problem. (i.e. if the error you encounter reads "FIELD_CUSTOM_VALIDATION_EXCEPTION: Placing a case on-hold requires a follow-up date", you'll want to check the validation rules listed under the Case object to see which one contains the error "Placing a case on-hold requires a follow-up date".)
If you are an Email to Case Premium user and are encountering this error during inbound email processing, you may consider adding some criteria to your validation rule so that it does not apply to your Email to Case Premium Context User.
If you are encountering a validation error when using a Vicasso application, you will also encounter the error by performing the same action manually. For example, if you are using Case Merge Premium and had encountered a validation error upon merging cases such as "FIELD_CUSTOM_VALIDATION_EXCEPTION: Case cannot be closed without a Reason", try manually closing out the case you selected as the child case. You should also encounter the same error upon manual case closure if the Reason field is not populated.
For additional tips / tricks for configuring validation rules, please see the following articles:
Note: Vicasso support may be able to help identify / provide a link to the problematic validation rule, but cannot provide direct assistance in updating the criteria of the validation rule. For more information on supported vs. unsupported issues, please see the following knowledge article.
This is the expected behavior of Salesforce validation rules and is by design.